In an interior space of a building, it is required to ensure an appropriate interior environment by air conditioning control with energy consumption as small as possible. In the event of ensuring an appropriate interior thermal environment, it is important to consider a thermal sensation such as heat and cold sensations felt by a person.
In the case where, in an amount of heat generated by the person (sum of radiant quantity by convection, heat radiation amount by radiating body, amount of heat of vaporization from the person, and amount of heat radiated and stored by respiration), a thermal equilibrium thereof is maintained, then it can be said that human body is in a thermally neutral state, and is in a comfortable state where the person does not feel hot or cold with regard to the thermal sensation. On the contrary, in the case where the thermal equilibrium is disturbed, then human body feels hot or cold.
There is an air conditioning control system that achieves optimization of the air conditioning control by using a predicted mean vote (PMV) as an index of the human thermal sensation, which is based on a thermal equilibrium expression. The air conditioning control system using the PMV receives, as variables affecting the thermal sensation, six variables, which are: an air temperature value; a relative humidity value; a mean radiant temperature value; an air speed value; an activity (internal heat generation amount of human body) value; and a clothes wearing state value. Then, the air conditioning control system calculates a PMV value.
Among the six variables to be inputted, those measurable with accuracy are the air temperature value, the relative humidity value, and the air speed value. Since it is difficult to directly measure the activity value and such a clothing amount value, values set therefor are usually used. However, it is desired to also measure the activity value and the clothing amount value in real time with accuracy.
Accordingly, as a technology for measuring an activity amount of a person who is present in a room, there is a human body activity amount calculation apparatus described in document 1 (JP 8-178390 A).
In the human body activity amount calculation apparatus described in document 1, human body in a room is imaged by imaging means, and an activity amount thereof is calculated based on an image thus obtained. Therefore, the activity amount of the person can be obtained without contacting human body thereof, whereby accurate air conditioning control can be performed.